【 Weak current college 】 computer fault diagnosis (7)

LAN class failure
First, define an example

Such a failure is primarily concerned with LAN broadband network and other failures in the network environment.

Second, the possible failure phenomenon

1, the network adapter does not work, led status is not correct;

2, network connection is blocked or only few machines cannot surf the Internet, can Ping pass but not networking, network transmission speed;

3, data transmission errors, network application error or panic, etc.;

4, the network is working correctly, but an application should not use the network;

5, can only see their own or individual computers;

6, a diskless station does not have access to the Internet or start an error;

7, network devices installed exception.

8. When you pass-time access to the network.

Third, the part may be involved

Network cards, switches (including HUB, router, etc.), network cable, motherboard, hard disks, power supplies, and other related parts.

IV. judgments points/order

1. preparation before maintenance

1) available in the network cable (straight line and normal network cable, the cable in order to meet international standards);

2) such as conditional with Internet line connection checker.

2. the environmental inspection

1) power supply connection check:

A. AC wiring definition is correct;

B. is there a ground wire;

C. the devices on the network (such as a HUB, switch, etc.) have been working on.

2) cable check:

A. whether the network cable connector-sequence and network connectivity requirements (such as direct-attached and network cable);

B. network cable connectivity is functioning, to view the network cable is not damaged, excessive distortions;

C. network cable length is too long (over category 5 twisted-pair cable length specification of 100 metres);

D. network cable connector-Crystal head isintact, whether oxidation;

E. the NIC interface is intact. Back to plug the network cable to check the network cable and network adapter connection is loose;

F. whether the requirement under the cable has a finalizer, the finalizer is normal.

3) network equipment appearance and surrounding checks:

A. powered-up, network connection led is off, etc.;

B.HUB equipment of network cable interface, in connection with a terminal or server, if the terminal or server startup and configuration correctly, the LEDs will light up (note the led colors correctly, refer to equipment manuals), if the led is not lit, the devices have failed;

C. card part is patch in place not tilted and card edge connector for oxidation;

D. network cable or switches and other equipment around whether there is interference.

4) host Visual inspection:

A. check whether foreign objects inside the chassis caused short circuit;

B. in the chassis is excessive dust and, if so, should be cleaned of dust;

C. the motherboard and network adapter components for deformation and discoloration;

D. power on, parts, components and other equipment for the unusual smell, temperature anomalies, etc.

Other areas: 5)

A. under UNIX, to distinguish between a Terminal panic or a server crash

3. fault points

1) for user management.

First of all should, as far as possible, and network management to get network management cooperation.

2) network environment checking:

A. for off line, packet loss, failure, it is necessary to pay attention to check the NIC and switch between compatibility;

B. network connects fine, but not for domain logon, to check from the following points:

A domain name is specified) exists or is already working;

B) has been made by the server, xx system requirements (such as on the server side to enable WINS resolution service, DNS services, WINXPHOME Editioncannot log on to the domain. ), Set terminal allows you to log on to the domain, the computer names are registered to the domain;

C) checks for proper use of protocols;

C. check installed firewall, whether it is authorized to access;

D. If necessary, use the straight line only connect two machines in a peer-to-peer network environment to check whether a connection network (this would exclude the network impact of various environmental factors).

3) network adapter driver and the property inspector:

A. driver is correct and appropriate. NIC device recommended by the system to automatically identify, as far as possible, to use and make the system matches xx and the updated driver (only older ISA interface card to use the manual installation method driven installation). When you install the driver, if necessary, will launch the loaded and running programs off the installation again.

B. network connection in a network environment is not working properly, you can adjust the speed, such as for 10/100Mbps network card, if you work in a 10Mbps network environment, the network is not working properly, you should specify the network card in the speed of 10Mbps.

C. check the network communication, such as whether to full-duplex, etc.。

4) network protocol checks:

A. check the network protocol, and other settings are correct (no matter which protocol, must ensure that the network protocol used on the machine). Network for the computer name of the same name;

B. If you cannot see their own or another computer, first by pressing F5 Refresh several times to check, and then check if installed and enabled for file and print sharing service, whether to add the NETBEUI Protocol (if the network has a WINS server, you do not need to add, if not for you to add);

C. If ping-network, but cannot access the network neighborhood or other Terminal Server, use the ipconfig/all (command line) and netstat commands to view specific information, check your network properties settings, such as domain, workgroup, and make the appropriate changes.

D.TCP/IP protocol utilities ping command to check the network's work. This requires maintenance personnel about the knowledge of the TCP/IP Protocol (order: PING127.0.0.1, native IP, Ben Wang section IP, gateway, DNS, etc.);

E. If the ping is disconnected, attempting to network properties to all adapters and Protocol deleted, restart after the installation;

F. perform tracert command, check the IP packet error in which segment;

5) system setup and application check:

A. check the machine self test is completed, a list of resources are listed in the NIC is one (non-PNP card excluded), its resources and other equipment are shared;

B. check the system if there are any resources used by the network adapter that conflicts with other devices, if any, through the replacement of the installation location of the device, or manual change conflict xx. Network card for ISA bus, you may need to switch off its CMOS in occupies disruptive PnP property, and the resources used by it and other equipment in General. Older PCI devices are advised not to share resources with other equipments;

C. check your system for viruses;

D. If a specific application when using network is not working properly, check the CMOS settings are correct, check the network card driver whether to match it, if necessary, close other applications that are running, and start the programs in the add-in, see if it works or works of the application of the machine, check the configuration;

E. reinstalling your system because the system of the network is not working properly.

6) hardware check:

A. use adapter comes with program and network connection detection of short circuit ring network adapters are intact;

B. replace the network card is not working properly, you can replace the motherboard, and replace the motherboard is still not resolved, you may consider replacing other types of cards;

7) for a diskless station, check the following points:

Whether to allow the A.BIOS network booting, it is best to disable the floppy drive in the BIOS, "ReportNoFDDForWin95" from Yes to No (or vice-versa. This floppy drive settings)

B. for ISA network card, the settings of the BIOS, should enable the BOOTROM of the default starting address as D800H or C800H, I/O for 300H (such as some network cards default to C800H easily with AGP video card, and other parts of the address resource conflicts cause installation to fail). ；

C. in the xx for invalid, on some motherboards, shielding onboard sound, and then make the appropriate modifications.

D. workstation Protocol must be consistent with the server protocol;

E. have more than one server, you must specify the first response to the server.

If you have a wireless network, special attention should be paid to:

A. check the two Terminal from the effective distance is too great, the middle is quarantined objects;

B. a peer network, the use of frequency channel is consistent;

C. use AP, terminal network ESSID must be consistent with the access point;

D. check the network card and AP key matches the key.

5. case

Case 1:

Problem description: the network adapter does not work, led status is not correct;

Solution: first observation system device manager has no network connection to the device, if not then replace the network card or Reseat the card testing and watch Goldfinger part have no rust, and if so, then use the eraser to clean test.

Case two:

Problem description: LAN, only a few machines can be networked, most not visits. Network interface card, HUB lamp lights flashing

Solution: to see this situation, both from the soft and hard to analyze, first:

A, software, using the latest version of the enquiries, KV3000 killviruses work, did not find any viruses, thus excluding the possibility of interference with a virus. Network connection, install NetBEUI, IPX/SPX and TCP/IP Protocol, the network adapter driver is properly installed in equipment management found no conflict, and the protocol binding. Setting up file and printer sharing, or set the workgroup name and computer name. It should be said from the network protocol to a shared resource settings etc. are no problem, you can exclude software error.

> B, analysis from the hardware side, generally there are four possible: one is the cable circuit breaker, unable to form a signal loop; the second is the network cable to the line sequence is correct; the third is the connection between a hub and a computer with a network cable is too long, more than 100 meters; its four hub port. For these four possibilities, make troubleshooting individually. Use the line tool or multimeter measuring cable, discover network cable connected condition, no circuit breaker. By visually connecting the network cable length cannot be more than 100 m. Several network has connected computers connected to the hub of Jack wrap to suspect that a corrupted hub port, the computer still interworking, hub port is not corrupted.

C, through a network cable to the line sequence of check and found that users make the line sequence is 1, 2, 3, 4, the answer lies here, because the RJ45 jack correct connection should be used 1, 2, 3, 6, 1, 2, is a snapline, 3, 6, is a line, the other four line is not defined. Identified problems, just as users do net head, insert after the network correctly.

Case 3:

Problem description: brain in "network places" can only see their own, and do not see the other computer, so you cannot use the other computer's shared resources, and shared printers

Solution: use the ping command to ping the local IP address or host name, check the NIC and IP network protocols are installed fine. If you can ping Tung, the computer's network adapters and network protocol settings are no problem. The problem is in the computer and network connection. Therefore, you should check the network cable and Hub and Hub interface status, if you are unable to ping a pass, only the description there is a problem with the TCP/IP protocol. Reset the network protocol, for the 10 following machine without the machines on the Internet may consider using NetBEUI protocol, if you used on the Intrnet TCP/IP Protocol, no matter which protocol, must ensure that the network protocol used on the machine.

Case 4:

Problem description: diskless station does not have access to the Internet or start an error;

Solution:

NOVELL diskless workstation doesn't login servers have the following situation:

A £ ® workstation appears on the screen "OR" Erroropeningbootdiskimagefile "Unabletoopenimagefile"

This may be connected to a remote boot image file is not included. Put the boot image file to copy into the server's Login directory; if you are using multiple remote boot image file, check whether the workstation Bootconf.sys were set correctly, you should make sure that the network address and node address is correct, if the above are correct, there may be a remote boot image file, you can test the build start floppy disk image file can be a normal boot disk station. If it is not enough, you can run RPLFIX utility.

B £ ® workstation screen appears "Errorfindingserver"

To ensure that the hardware line connection no problem, check the server has been installed on the frame type "Ethernet_802.3", remote boot image file from net.cfg contains Ethernet_802.3, it is said the older IPX chip, it does not support Ethernet-802.2 frames. In accordance with the appropriate frame type reproduce the boot image file.

C £ ® workstation image file from a remote boot hangs during loading the drivers, the screen and displays the following similar information: Ethernetcardisimproperlyinstallornetconnectedthenetwork.

This is because earlier legacy IPX chip in Netware4.X above, in the remote boot image file does not have a remote boot image file rplodi.com or in a batch file that is no rplodi.com isl.com downlink.

D £ ® workstation display "LoadingMS-DOS" and pending

This is because the remote boot image file to use the DOS5.0 or above versions, on a remote boot image file to run RPLFIX utility.

E. "batchfilemissing appears on the screen."

This message is due to the autoexec.bat or other batch files (on multiple remote boot image using batch) does not exist in both the LOGIN directory and user login directory.